NO.26 A/C ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY [MZR-CD 2.2]

id0103f3822400

26

A/C ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY

DESCRIPTION

•  A/C compressor magnetic clutch does not disengage.

POSSIBLE CAUSE

•  A/C compressor magnetic clutch stuck engagement

•  A/C relay is stuck closed

•  Improper A/C compressor magnetic clutch clearance

•  Short to ground circuit between A/C relay and PCM

•  A/C relay to magnetic clutch circuit shorts to battery power

•  Communication error between instrument cluster and climate control unit

•  Communication error between PCM and instrument cluster

26	A/C ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY
DESCRIPTION	• A/C compressor magnetic clutch does not disengage.
POSSIBLE CAUSE	• A/C compressor magnetic clutch stuck engagement • A/C relay is stuck closed • Improper A/C compressor magnetic clutch clearance • Short to ground circuit between A/C relay and PCM • A/C relay to magnetic clutch circuit shorts to battery power • Communication error between instrument cluster and climate control unit • Communication error between PCM and instrument cluster

Diagnostic Procedure

STEP	INSPECTION	RESULTS	ACTION
1	Perform the self-test function using the M-MDS. Switch the ignition to ON (engine off). Retrieve PCM, instrument cluster and climate control unit DTCs. Are any DTCs displayed?	Yes	DTC is displayed: Go to the appropriate DTC test. (See DTC TABLE [MZR-CD 2.2].) (See DTC TABLE [FULL-AUTO AIR CONDITIONER].) (See DTC TABLE [INSTRUMENT CLUSTER].)
1		No	No DTC is displayed: Go to the appropriate DTC test. (See DTC TABLE [MZR-CD 2.2].)
2	Start the engine and run it at idle. Turn the A/C switch on. Remove the A/C relay. Does the A/C magnetic clutch disengage?	Yes	Go to Step 5.
2		No	Go to the next step.
3	Turn the ignition switch to off. Disconnect the A/C compressor connector. Start the engine and idle it. Does the A/C magnetic clutch disengage?	Yes	Inspect and repair for short to power supply between A/C relay terminal C and A/C compressor connector.
3		No	Go to the next step.
4	Verify that the A/C magnetic clutch clearance. (See MAGNETIC CLUTCH ADJUSTMENT [FULL-AUTO AIR CONDITIONER].) Is the magnetic clutch clearance normal?	Yes	Inspect and repair A/C magnetic clutch for stuck. (See MAGNETIC CLUTCH INSPECTION [FULL-AUTO AIR CONDITIONER].) (See MAGNETIC CLUTCH DISASSEMBLY/ASSEMBLY [FULL-AUTO AIR CONDITIONER].)
4		No	Adjust the magnetic clutch clearance.
5	Access PCM PID AC_REQ PID using the M-MDS. Monitor the PID AC_REQ while turning on and off the air conditioner by switching the control penal. Is the PID AC_REQ always ON?	Yes	Go to the next step.
5		No	Go to Step 7.
6	Inspect refrigerant pressure switch. (See REFRIGERANT PRESSURE SWITCH INSPECTION [FULL-AUTO AIR CONDITIONER].) Is the refrigerant pressure switch normal?	Yes	Replace the climate control unit. (A/C request signal always ON.) (See CLIMATE CONTROL UNIT REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER].)
6		No	Replace the refrigerant pressure switch. (See REFRIGERANT PRESSURE SWITCH REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER].)
7	Inspect the A/C relay. (See RELAY INSPECTION.) Is the A/C relay normal?	Yes	Inspect and repair for short to ground circuit between A/C relay and PCM terminal 1BX.
7		No	Replace the A/C relay.
8	Verify test results. • If normal, return to the diagnostic index to service any additional symptoms. (See SYMPTOM DIAGNOSTIC INDEX [MZR-CD 2.2].) • If the malfunction remains, inspect the related Service Information and perform repair or diagnosis. ― If the vehicle is repaired, troubleshooting completed. ― If the vehicle is not repaired or additional diagnostic information is not available, reprogram the PCM if later calibration is available. Retest.